Purpose: In this study we explored the effect of Agent Orange exposure on prostate cancer survival in VA (Veterans Affairs) patients receiving androgen deprivation therapy for advanced prostate cancer.
Materials and methods: We retrospectively examined the association between Agent Orange exposure in men with prostate cancer in national VA databases who were being treated with androgen deprivation therapy. Patients were diagnosed with prostate cancer from 2000 to 2008 with followup through May 2016. Clinical, pathological and demographic variables were compared by Agent Orange exposure. Associations of Agent Orange with overall survival, skeletal related events and cancer specific survival were performed using adjusted Cox proportional hazard models after IPSW (inverse propensity score weighted) adjustment.
Results: Overall 87,344 patients were identified. The 3,475 Agent Orange exposed patients were younger (p <0.001), had lower prostate specific antigen (p = 0.002) and were more likely to receive local therapy and chemotherapy (p <0.001) than the 83,869 nonexposed patients. The Charlson comorbidity index was similar in the groups (p = 0.40). After IPSW adjustment Agent Orange exposure was associated with improved overall survival (HR 0.84, 95% CI 0.73-0.97, p = 0.02). However, no difference was observed in the risk of skeletal related events (HR 1.04, 95% CI 0.80-1.35, p = 0.77) or cancer specific survival (HR 0.79, 95% CI 0.60-1.03, p = 0.08).
Conclusions: Agent Orange exposure was associated with a decreased risk of death in men receiving androgen deprivation therapy for advanced prostate cancer. It does not appear to be associated with worse oncologic outcomes.
Keywords: Agent Orange; analogs and derivatives; gonadotropin-releasing hormone; hospitals; prostatic neoplasms; veterans.